Available from July this year (although pricing is yet to be announced), the Tiagra disc brakes (or RS405 disc brakes, to give them their proper title), are fully hydraulic, hopefully meaning more braking power and better modulation than what is offered by standard rim brakes.

The system features many trickle down features from the higher level Shimano disc brakes, such as the Ice Technology, which means that there are cooling fins are built into the rotors (which will be available in 140mm and 160mm sizes), apparently helping with cooling on long, technical descents.

There are now only a couple of missing pieces in the Shimano disc brake puzzle

The brake/shifting levers and hoods look pretty similar to the 105-level disc brakes that were released last year, which, if we’re being honest, don’t look too great in the image at the top of the page. Maybe they’ll grow on us when we see them in the flesh.

But as for their function, Shimano describes the RS405 shifting system as “ergonomically pleasing for multiple hand sizes”, partly thanks to the fact that the reach of the lever can be adjusted by up to 10mm to suit riders with smaller hands, while the “Vivid Index Shifting on the 10-speed shifting system equates to light shifting effort with a defined click engagement”.

As you can see from the table above this means that there are now only three Shimano road groupsets that don’t have disc brake options sitting alongside them: Shimano Claris and, more interestingly, Dura-Ace and Dura-Ace Di2. Could we see this rectified in the expected new Dura-Ace groupset later this summer? That now looks ever more likely.

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